1. Technical Field
Embodiments of the subject matter disclosed herein generally relate to methods and systems and, more particularly, to mechanisms and techniques for attaching parts to a body of a ram blowout preventer.
2. Discussion of the Background
During the past years, with the increase in price of fossil fuels, the interest in developing new production fields has increased dramatically. However, the availability of land-based production fields is limited. Thus, the industry has now extended drilling to offshore locations, which appear to hold a vast amount of fossil fuels.
The existing technologies for extracting fossil fuels from offshore fields use, among other things, a blowout preventer (BOP) for preventing well blowouts. The BOP is conventionally implemented as a valve to prevent the release of pressure either in the annular space between the casing and the drill pipe or in the open hole (i.e., hole with no drill pipe) during drilling or completion operations. However, various components of the BOP need to be replaced from time to time. An example of a BOP 20 is shown in FIG. 1. The BOP 20 shown in FIG. 1 has, among other things, two ram blocks 22 that are supported by respective piston rods 24 and a corresponding locking mechanism 26. The locking mechanism 26 is configured to lock the rods 24 at desired positions. The two ram blocks 22 are configured to move along a direction parallel to a longitudinal axis of the piston rods 24. The ram blocks 22 may sever a drill string 28 or other tools that cross a vertical wellbore 30 of the BOP 20. However, after cutting the drill string 28 for a number of times, the ram blocks 22 and/or their respective cutting edges need to be inspected and sometimes reworked/replaced. Alternatively, if the ram blocks 22 are designed to seal the well and not to cut a tool, an elastomer provided on a face of the ram blocks 22 needs to be replaced after a certain number of closures of the BOP. For this reason, the BOP 20 of FIG. 1 is provided with a bonnet 32, for each ram block 22, which, for a particular BOP design, can be opened for providing access to the ram blocks. FIG. 2 shows the bonnet 32 having a hinge 34 that rotatably opens the bonnet 32.
However, those skilled in the art would recognize that regular service of the BOP is required for changing the blades and/or elastomer attached to the ram blocks. Thus, the BOP bonnets frequently need to be separated from the BOP body to expose and service the ram block. The operation of separating the bonnets from the BOP body is no easy task, and frequently requires special tooling sized to accommodate the large diameter bolts. Such an operation may require several eight-hour shifts of skilled technicians. However, the concern is the amount of down time for the entire rig, which cannot function without the BOP, as millions of dollars of drilling equipment may be idle during the BOP service operation.
A solution to this problem is to design BOPs with bonnet-less “doors.” However, these designs have other undesirable features. One design utilizes a removable bar (see Brugman et al. U.S. Pat. No. 5,975,484, the entire disclosure of which is incorporated herein by reference), that must be handled and stored when accessing the ram cavity, which can lead to damage or injury during the handling of the bar. The other design has design features that make it expensive to manufacture.
Accordingly, it would be desirable to provide a BOP design that has quick opening features but has a locking mechanism that does not require removal of any supporting parts and is not expensive.